1. Technical Field
The present invention relates to the manufacture of a printed circuit board, and more particularly, to a method for removing a seed layer in manufacturing a printed circuit board and a printed circuit board manufactured by using the same.
2. Description of the Related Art
In accordance with the recent trend of miniaturization and high functionalization, high integration of an electro circuit is required, and therefore, it is important to reduce width and space of a copper wiring in a printed circuit board (PCB). In addition, to this end, a semi additive process (SAP) scheme in which a seed layer is formed by sputtering, and an electroplating layer for forming a circuit pattern is then formed has become prominent.
In manufacturing the printed circuit board using the SAP scheme, after an electro plating process and removal of a photo resist are completed, a tie layer and the seed layer need to be removed. Here, in the case of removing the tie layer and the seed layer using a wet etching scheme, since a form in which the tie layer and the seed layer are etched is not elaborate, serious problems such as damage to a wiring or disconnection may occur in a fine pattern of the copper wiring. Therefore, it is required to use a dry etching method rather than a wet etching method in manufacturing the printed circuit board. To this end, methods such as reactive ion etching (RIE) or laser ablation have been used.
Meanwhile, in removing a redistribution layer (RDL) seed layer by using the laser ablation, there are problems as follows.
1) In the case of a circuit pattern of 5 μm or less, problems occur in resolution of the pattern.
2) Since a laser having large energy (for example, energy of 650 mJ/cm2 or more in the case of an excimer laser) is used, there is a risk that reproducibility and an electroplated copper RDL are damaged at the time of repeatedly performing work.
3) Since energy of 650 mJ/cm2 or more needs to be accumulated in the seed layer, a relatively long processing time is required for a laser scanning.
Therefore, in order to effectively etch the pattern of 3 μm or less, an improved technology is required.